This invention concerns a flame-retardant non-woven textile article manufactured by bonding of fleece without a binder.
Flame-retardant woven textile articles are known from the literature. Usually, this entails treating a textile with one or more flame-retardant compounds. Substances containing phosphorus, in particular, have made a name for themselves in their capacity as flame-retardant compounds. Therefore, the treatment of cellulosic textile woven articles with flame-retardant compounds containing phosphorus has been described in numerous patent letters, such as the U.S. Pat. No. 5,135,541; U.S. Pat. No. 4,494,951; U.S. Pat. No. 4,487,800; U.S. Pat. No. 4,078,101 and U.S. Pat. No. 4,145,463.
What all these described procedures have in common is that the treatment with flame-retardant compounds is carried out on the textile after its manufacture.
Furthermore, it is known from the literature how flame-retardant non-woven textile articles may be manufactured. U.S. Pat. No. 3,906,136, for instance, describes a technique for producing flame-retardant textile articles by adding a derivate of hexahydrotriazinphosphonate to the textile, the phosphonate being subsequently cured to form a resin. This technique applies, among others, to non-woven cellulosic textile articles, too.
It is known from U.S. Pat. No. 2,983,623 that fibres and textiles can be treated with a mixture of tetrakis-hydroxymethyl-phosponiumchloride (THPC) and urea in the course of which a network-like polymer compound results in the textile article as a result of subsequent curing. The application of this technique to non-woven textile articles is mentioned.
With these known procedures, too, treatment using the flame-retardant compound containing phosphorus is carried out on the textile article after its manufacture. Additionally, a bonding always takes place because of the curing of the added compounds. In the context of manufacturing non-woven textile articles this process corresponds to bonding using binders or adhesive agents. This results in increased stiffness as well as a high area weight of the product which, in many fields of application, is not desired. Textiles which have been made flame-retardant in this way are also likely to release substances containing phosphorus while in use, producing unpleasant irritations to the skin. On top of that, the resin-producing substances applied pose a strain on the environment.
For all these reasons, the production of flame-retardant non-woven textile articles which are unaccompanied by the above-mentioned disadvantages and side effects has been attempted. In particular, efforts have been made to achieve bonding of the source material, namely the fleece, without adding additional substances.
EP 0 447 605 A1, for example, describes the manufacturing of a flame barrier with an area weight of 40 to 100 g/m2 made of a fleece by bonding the fleece using high-energy water jets, with the fleece textile consisting of partly graphitized polyacrylnitrile fibres.
The bonding of fleece using water jets has become known as "hydro-entanglement" or "spun-laced technology". The procedure entails the entanglement of the individual fibres of the fleece by means of water jets which are substantially directed in vertical manner onto the fleece under a certain pressure.
The disadvantage of the EP 0 447 605 A1 flame barrier is that polyacrylnitrile fibres are not biodegradable. Furthermore, the graphitizing of the polacrylnitrile fibres before their processing to the product involves one further costly process step. Furthermore, the black color of the evolving textile article which results from graphitizing makes the application of the article very difficult in many areas.
WO 93/13249 describes a process for the manufacture of a cellulosic product which contains polysilicic acid, the polysilicic acid being partly modified with aluminium silicate. Such products, and fibres in particular, are obtained by adding SiO2 to a solution of cellulose, such as viscose, in the form of polysilicic acid. This solution is then spun into fibres which incorporate chains of polysilicic acid. According to example 4 of this application, staple fibres produced in this way can be bonded to non-wovens using water jets.
The disadvantage of these known products is that the tenacity of the spun fibres, and therefore the tenacity of the products resulting from this technique, is low in comparison with fibres made by the usual viscose process. This means that these products do not lend themselves to certain specific fields of application.